The invention concerns a multiway valve with two valve positions, and, in particular a 4/2-way valve whose connections are always interconnected in pairs. The present invention makes it possible to change the pairwise association of the connections by switching over from one valve position to the respective other valve position. The valve housing is provided with an axial hole which has a plurality of steps to form seat elements located in series and includes two end chambers and an intermediate space therebetween, into which one of the connections opens. A spool-type drive pin carrying at least two closing elements is located in the axial hole, the drive pin being guided so as to seal in the region of a first of the two chambers. One of the connections also opens at least into the second chamber, and the drive pin has an inner longitudinal passage which is connected by at least one radial hole to the first chamber at one end and opens at the other end into the second chamber on the associated end of the drive pin. The closing elements which interact at least partially elastically and flexibly with the seat elements each are of a sleeve-shaped or annular configuration.
Multiway valves are often constructed as straight-forward spool valves. Although such spool valves are of relatively simple design, they are relatively sensitive to dirt, thereby causing the valve spool to be jammed by dirt in extreme cases. Seat-controlled valves, on the other hand, are relatively insensitive to dirt. A relatively high level of design complexity is, however, generally necessary if, in one valve position, a plurality of closing elements are simultaneously to rest on associated seat elements.
DE-OS 37 00 899 discloses a multiway valve of the initially indicated type which is of hybrid construction providing seat-controlled valve elements, on one hand, and spool valve elements, on the other hand. Although this arrangement ensures that only one closing element of a seat-controlled valve element must interact with an associated seat element in each valve position, because spool valve elements also become effective in each valve position, nevertheless the danger of jamming of the spool valve elements exists in principle in this known multiway valve.
A 5/2-way valve is already known from U.S. Pat. No. 3,779,280 in which, however, one of the connections is completely shut off in each valve position. This 5/2-way valve includes a control rod extending through the housing, and closing elements displaceably located on this control rod in the form of a plurality of discs having a diameter which is relatively large compared with the control rod. These discs interact with valve seats on the housing. The discs are located in pairs on the rod, and a spring is provided between the two discs of each disc pair. These two discs, located between two stops on the rod, are forced apart in the direction of the stops by the spring. The control rod is guided to the outside through one closing cap at each end and is supported outside the valve space.
With this known arrangement, it is impossible to exclude the possibility that the discs, which have a relatively large diameter, may tilt and tip while being displaced on the rod. The design length is also relatively large, because the rod is guided through closing caps at both ends to the outside for support. Another unfavorable feature is that only directly adjacent valve spaces or chambers can be connected to one another in this valve. Because, moreover, one of the connections is completely shut off in each valve position, this valve is unsuitable from the outset for an application such as one in which the connections always have to be interconnected in pairs and in which only the pairwise association of the connections is to be changed when switching from one valve position to the respective other valve position.
A 3/3-way valve with a control rod having a through hole is disclosed in DE-OS 26 50 701. This control rod is subjected to two control forces acting in opposite directions and carries a displaceable valve body supported by a spring on the valve housing and by a further spring on the valve rod. In this arrangement, the valve body forms a first inlet valve by way of a contracted edge of the housing and a second inlet valve by way of an edge provided on the valve rod. The valve rod, guided and supported at one end, is located between two valve spaces which can be connected together by the hole provided in the rod and, in each of which, is located a piston acting on the relevant end of the rod.
In addition to having a relatively complicated construction, this valve also has the disadvantage that it is possible, because the valve rod is only guided and supported at one end, that the valve rod may be deflected laterally at its free end due, for example, to an external shock load or the like. This can lead to impairment of the valve function particularly since the valve bodies are provided on this free and unguided end of the valve rod.
Finally, DE-PS 37 39 198 relates to a fuel injection pump for internal combustion engines. This pump has a pump inner chamber and a regulator space, separate therefrom, having a regulator which serves to adjust the respective volume of fuel injected. In this arrangement, apparatuses are provided to be capable of compensating the temperature for the measured volume of fuel.
An object of the present invention is to provide an improved multiway valve of the initially indicated type which, on one hand, is relatively insensitive to dirt and, on the other hand, has a simple and compact construction, so that a high level of functional reliability is ensured at all times.
This object has been achieved according to the present invention in that at least four seat elements located in series and at least two intermediate spaces located between the two end chambers are provided in the multiway valve, and the drive pin is radially supported in the region of its end close to the second chamber by radial protrusions provided on its outer periphery. The closing elements include two oppositely directed sealing surfaces which can be laid on one or other seat element of the associated seat element pair, depending on the valve position. A first of the closing elements directly adjoins the radial protrusions in the direction of the second chamber.
The present invention not only combines the advantages of spool valves with those of seat valves, but also achieves the result that, in addition to insensitivity to dirt, optimum functional reliability is provided. Surprisingly, the multiway valve can also still be constructed in an extremely simple and compact manner and can be manufactured without difficulty. Because support and guidance of one end of the drive pin within the axial hole of the valve housing takes place via the radial protrusions, this end of the drive pin with the end passage opening can be located within the axial hole, and in particular within the second chamber, so that it is also possible to produce a connection between both end chambers without difficulty, by way of the longitudinal passage provided in the drive pin, with optimum support and guidance of the drive pin at both ends.
The longitudinal passage opening into the second chamber at one end of the drive pin can be manufactured without difficulty because the relevant hole can be made from the aforementioned drive pin end. The sleeve-shaped or annular closing elements, preferably having only a slightly larger external diameter than the drive pin, can be pushed onto the drive pin without difficulty. Together with the respectively adjacent closing element, the radial protrusions and the relevant seat elements on the housing act to ensure the relevant valve function. Thus the relevant mutually adjacent valve spaces are connected together by the intermediate spaces located between the radial protrusions when the closing element is lifted from the valve seat whereas, when the closing element is in contact with the seat element, these spaces are shut off from one another.
Because at least one part of the closing elements interacts elastically flexibly with the seat elements, there is reliable compensation for tolerance which further increases the functional reliability of the multiway valve. The closing elements or the seat elements or both can be arranged or configured to be elastically flexible. In addition, it is possible, in contrast to spool valves, for the valve housing to be made of plastic.
If the drive pin end opposite to the passage opening in the end is guided and supported so that it seals, a setting unit acting on the drive pin can be associated with the free end of this drive pin emerging outwards through the wall at the bottom of the hole in accordance with the present invention.
The second closing element can be used to shut off the intermediate space adjacent to the first chamber from a further intermediate space adjoining it in the direction of the second chamber, in one valve position, and to shut off the first chamber from the intermediate space adjacent to it, in the other valve position.
The annular end surface of the drive pin incorporated in the present invention provided in the region of the relevant longitudinal passage opening simultaneously acts as the sealing surface of the first closing element which interacts with the bottom of the second chamber acting as a seat element. The interconnection between the connection opening into the first chamber and the connection opening into the second chamber is therefore interrupted in that, in the relevant position of the drive pin, the end surface of the drive pin with the passage opening is held against the bottom of the second chamber. The preferred connection paths are such that the first and second end chambers and the intermediate spaces, and, on the other hand, the closing elements are located and configured such that, in one valve position, only the first end chamber is connected to the adjacent intermediate space and the second end chamber is connected to the intermediate space adjacent thereto it and, in the other valve position, only the first end chamber is connected, via the inner longitudinal passage, to the second end chamber and one intermediate space is connected to the other intermediate space.
Whereas the first closing element or the annular flange can be permanently connected to the drive pin in one embodiment, it is useful for the second closing element to be displaceable relative to the drive pin and spring-loaded in order to achieve the desired compensation for tolerance.
A passage opening into the intermediate space adjacent to the first chamber can be connected via the first chamber, and the longitudinal passage formed in the drive pin and the second chamber to the connection opens into this second chamber. The interconnection between these two connections can be interrupted in that the first chamber can be shut off from the intermediate space adjacent to it by the first closing element. The first chamber is exclusively and continuously connected via the longitudinal passage in the drive pin and the second chamber to one of the connections. This connection is formed by the connection opening into the second chamber. The drive pin end surface with the passage opening is at a distance from the bottom of the second chamber in each of the two valve positions. Because the first closing element is located in the intermediate space adjacent to the second chamber, this intermediate space is connected to the intermediate space adjoining it in the direction of the first chamber in one valve position, and is connected to the second chamber in the other valve position.
In a configuration of the present invention in which the ring is arranged to be spring-loaded by a compression spring pushed onto the drive pin and supported at one end on the ring and at the other end on a stop on the drive pin, it is thereby achieved that, depending on the position of the drive pin, one of the two rings is in sprung contact with an associated seat element whereas the other ring is held by the radial protrusions against a seat element associated with it. In this case also, therefore, optimum compensation for tolerance is always ensured.
It is useful for the drive pin to be spring-loaded into a first valve position and to be movable against the spring force into a second valve position by way of the setting unit. One presently preferred configuration of the seat elements is that the seat elements are at least partially formed by annular end surfaces of annular grooves opening into the axial hole.
A temperature sensor for the temperature of the fluid in the valve can also be provided and is particularly useful if the multiway valve is inserted in a fuel injection system of an internal-combustion engine.
A particularly advantageous way of arranging the multiway valve of the present invention in a fuel injection system of an internal-combustion engine such that preferably in the form of an electrical NTC thermistor, temperature sensor is located in one of the second end chamber and in a connection.